The present invention relates to flow rate control, and more particularly to flow rate control of a fluid in increment steps.
During ramjet testing it often is desirable to bring the engine to a certain operating condition, i.e., fuel flow to engine, hold for a short time to take necessary data, then change to a new point. In the past the fuel has been controlled by a hand operated needle valve. A typical ramjet engine combustor test lasts about 30 seconds; usually because the engine is in a developmental stage and has little or no thermal protection. Having only 30 seconds, the operator tends to move the needle too fast, never stopping. The engine stays in a transient state during the entire operation, thus giving invalid data.
Also, it is often desirable to compare different engine configurations operating with the same fuel flow. With the needle valve fuel control and an automated data acquisition system, the operator seldom settles on the same fuel flow point twice.